This invention relates to fuel bundles for placement in channel contained fuel bundles for use in boiling water reactors. More importantly, an improved fuel bundle is disclosed which utilizes partial length rods extending from the bottom of the assembly to the regions of the fuel assembly in which two phase steamwater flow occurs. These partial length rods can be symmetrically or asymmetrically distributed in the interior of the assembly, with the preferable location relative to the channel side walls of a bundle of rods or fuel assembly, contained within a fuel channel of a boiling water reactor, depending on whether nuclear or thermal hydraulic performance was being optimized.